The proposed work seeks to investigate various forebrain sites of dipsogenic action of the hormone, angiotensin II. Attention will be focussed on the subfornical organ, and tissue of the diencephalon bordering the optic recess of the third ventricle. Both regions have been suggested in recent literature to be sites at which angiotensin II acts to provoke drinking. Direct intracranial injections of the hormone as well as selective experimental lesioning techniques will be used to investigate the interactions or independence of these two suggested sites of action of angiotensin II.